This invention relates to drying apparatus especially adapted to domestic use for drying clothes, but which may be advantageously used for drying various articles in industry.
More particularly, the invention relates to a dryer apparatus comprising an enclosure which contains a drying chamber for receiving articles to be dried, an air heating passage and an air cooling passage, wherein the heating passage is situated underneath the drying chamber and has inlet means and outlet means communicating therewith on opposite sides of said chamber, respectively, air heating means being provided in the heating passage between the inlet and outlet means thereof to heat air flowing through said heating passage, and wherein the cooling passage is situated beside the drying chamber and has inlet means through which the drying chamber communicates with the top of the cooling passage and outlet means at the bottom of the cooling passage, which outlet means communicate with the heating passage near the inlet means thereof, air cooling means being provided in the cooling passage, between the inlet and outlet means thereof, to condense moisture from air flowing downwardly in the cooling passage, and water collecting or draining means being provided underneath the outlet means of the cooling passage to collect water dripping from the cooling means, the arrangement being such that a major air flow is circulated between the drying chamber and the heating passage and a minor air flow is circulated from the drying chamber to the heating passage through the cooling passage.
A dryer apparatus of the above kind is known from British Patent Specification No. 1,133,098 to Randell.
In such known apparatus the inlet means of the cooling passage are constituted by an interspace between two vertical walls facing each other. The inlet of the interspace is a slit near the bottom of the drying chamber. The top of the interspace communicates with the top of the cooling passage.
It is known that energy can be spared, when drying clothes or the like, in an apparatus of the above kind by flowing a minor proportion of the air through the cooling passage and circulating a major proportion of the air through the heating passage and the drying chamber only. The energy spared is due to the fact that a relatively low air flow past the cooling means gives rise to a relatively low loss of sensible heat from the moist air and thus the heating means require relatively low energy to make-up the sensible heat which has been removed by the cooling means.
In the Randell apparatus the flow path to the cooling passage has its inlet at the bottom of the drying chamber and thus it is practically impossible to obtain a downward air flow in this passage by convection. A fan or similar blower is therefore necessary to this purpose. The fan must be in operation from the very beginning to the end of the drying cycle of the apparatus. A great proportion of the energy which would be spared by circulating only a minor proportion of air through the cooling passage is thus lost in energising the fan.